Crimped flat material for filter plugs



Aug. 8, 1961 P. A. MULLER CRIMPED FLAT MATERIAL FOR FILTER PLUGS FiledApril 1a, 1955 2 Sheets-Sheet 1 Him. AD /f Mange, INVENTOR.

Arron/w: Y5

1961 P. A. MULLER 2,995,481

CRIMPED FLAT MATERIAL FOR FILTER PLUGS Filed April 1a, 1955 2Sheets-Sheet 2 Fig. I3

PAUL. ADOLF MULLER, mmvron.

ATTORNEYJ United Statcs Patent 2,995,481 CRIMPED FLAT MATERIAL FORFILTER PLUGS Paul Adolf Miiller, Herrliberg, Switzerland Filed Apr. 18,1955, Ser. No. 502,016 Claims priority, application Switzerland Feb. 15,1955 laims. (Cl. 154-55) The present invention relates to crimped, i.e.grooved, fiat material, particularly crimped paper webs for smokefilters. This application is a continuation-in-part of my copendingapplication Serial No. 447,478, filed August 3, 1954, now Patent No.2,847,086, granted August 12, 1958.

Crimped papers are already known and, besides other purposes, are usedto an important extent for the manufacture of filters for tobacco,particularly for cigarettes. Since, with such filters, fiat webs ofpaper have to be shaped into cylindrical plugs, the paper used must haveonly a slight rigidity at least in one direction. A noncrimped web ofpaper would, on being compressed into a cylindrical cord, have irregularfolds and randomly distributed bulges, which would lead to an irregularweb cross-section with hollow spaces and unconnected ducts; that is tosay, the result would be a structure completely unsuited for filteringpurposes. Crimped paper, on the other hand, does not have thesedisadvantages and for this reason paper filter plugs are almostexclusively made with such material.

The crimping of the paper web, however, also facilitates the mechanicalmanufacture of such filter plugs and, furthermore, ensures that theywill have the necessary porosity.

Crimped paper has so far been produced almost exclusively by a generallyknown method in which an endless damp web of paper runs on to a heatedcylinder, dries there to a certain extent and is peeled off by a bluntscraper, the previously smooth paper web being upset in its direction oftravel and provided with cross folds. Thus, the material is compressedand the crimped web of paper is always heavier per unit of length thanthe previously smooth web, the increase in weight being proportionate tothe so-called crimping ratio. If, for instance, the originally smoothweb of paper is worked into crimped paper with a crimping ratio of 3:1,a unit of length of the final product can be stretched to three timesits length and ironed out into a smooth web; that is to say, in itscrimped state, it is three times as heavy as the smooth web.

With a web of paper crimped by this method the crimped folds and groovesrun transverse to the direction of travel. Although crimping of the webis indispensable, the fact that it runs transverse to the webcomplicates both the machines for the production of filters and theprocess employed therefor. As the filter cord is produced by the placingtogether of one or several paper strips of given width, which can onlybe done vertically to the crimped folds, strips of the aforesaid widthmust be cut ofi the broad crimped webs of paper so that these stripscannot be longer than the width of the crimped web. These strips arethen fed to the gathering attachment of the filter plug machine in thelongitudinal direction, i.e. parallel to the crimped folds.

In order to make continuous production possible, such longitudinallycrimped paper strips of limited length are arranged side by side andslid continuously into the gathering attachment. Apart from the cuttingand conveying devices thus required, which work intermittently and causean increased susceptibility to breakdowns, the small length of stripprovides a number of extremely troublesome shortcomings. In order toensure that the successive strips are properly introduced into thegathering attachment, strips wider than 4 to 5 cm. cannot be used; this,

as the material required is determined by the dimensions and thicknessof the filter card, makes it necessary to lay four to six crimped stripsone on top of the other and to work them jointly in the gatheringattachment, thus complicating the feeding apparatus still further. Sinceno other way of continuous manufacture has been known hitherto,extensive mechanical devices have been designed for the purpose and usedin practice. It has also already been suggested to paste the separatecrimped strips together by hand so as to permit continuous operation.

Apart from this feed difficulty, however, another drawback is that thefirst and last filter of every crimped strip of limited length have tobe considered as rejects as both may contain the junction point betweensuccessive strips. This must be avoided since with the strips which arenot pasted together part of the filter plug may easily drop out of thecigarette and with pasted strips the filtering effect is impaired by thepasted edge.

Thus there exists a need for new and improved crimped fiat material forfilter plugs.

The web of filtering material according to the invention ischaracterized by the fact that it is an endless web with a longitudinalstructure parallel to its direction of travel, consisting of alternatelythicker and less thick strip material.

A typical embodiment of the invention will now be described in detail inconjunction with FIGS. 1 to 13 of the attached drawing in which:

FIGS. 1 and 2 are a vertical and horizontal projection respectively of atypical embodiment of an arrangement for producing the crimped fiatmaterial according to the invention, shown diagrammatically;

FIGS. 3 to 10 are cross-sections and horizontal projectionsrespectively, arranged in pairs; each pair is intended to indicate on anenlarged scale the appearance of the web of material at different pointsas it passes through the arrangement;

FIGS. 11 and 12 are each cross-sections through a stretched, corrugatedweb; and

FIG. 13 shows a few samples of the material according to the invention.

The fundamental difference between the method of crimping fiat materialaccording to the invention and all previous crimping methods is thatrecognition, backed up by experience, is given to the fact that thecrimping process, contrary to the existing assumption, does notnecessarily result in a compression of the material per unit of length,but can also be achieved by stretching the structure of the material.This yields a web of material which, per unit of length is at the mostequal in weighteven less heavy in most casesto the smooth web ofmaterial. In spite of this, a substantial crimping ratio can beobtained, eg in the order of magnitude of 1:2, so that after the crimpedweb of material has been ironed smooth, it will have, per unit of lengthof the original web, dimensions which have become enlarged in the sameratio. Sections of equal area of the original web of material and of thecrimped web which has been ironed smooth again will then be different inweight, the ironed web being lighter in proportion to the crimpingratio.

The crimping and stretching processes are advantageously, but notnecessarily, carried out at the same time. Accordingly, the web of flatmaterial to be treated must be previously made yielding, which can bedone by spraying it with liquid, submitting it to steam treatment,heating it, passing it through a bath of liquid or in any other suitablemanner depending on the type of material. This treatment, however, iscarried out continuously on the web of material which is moved at aconstant speed.

The fiat material which has been made yielding, is subjected to acontinuous process of crimping and stretching, for instance by means ofsuitable stamping devices, grooves, being produced such that two narrowzones of material are kept rigid along each groove and the central zonein between is deformed. Owing to the lateral zones being kept rigid, thecentral zone can only be deformed if the material in it is stretched atthe same time. This process is carried out successively on a pluralityof parallel grooves and yields a web of material whose surface has beenenlarged at the expense of the thickness of the material at the pointconcerned. The differences in thickness transverse to the grooves of theweb of material can result, as required, in thinner groove walls andthicker edges or, conversely, in thicker walls and thinner edges. (FIGS.11 and 12.)

If, by way of example, the web of material is grooved in itslongitudinal direction, it will retain after the completed crimping andstretching process approximately the same width as before. If the webthus crimped is ironed smooth again, the resultant width of the web willbe enlarged by the amount of the crimping ratio.

The stretching of the flat material depends primarily on the depth ofthe individual grooves and may be greater or less according to the typeof material. If a web of material has to be more deeply grooved than iscompatible with its stretching capacity, grooving is carried out inseveral successive stages, it being possible for the web of material tohave a somewhat smaller width between each two stages. The final resultwill then be a crimped web of material which, although having the desired depth of groove, is less wide than the original smooth web; here,too, however, the surface is enlarged at the expense of the thickness ofthe material.

The crimped web of material generally requires an after-treatment,drying for instance, in order to re-harden it, and can then be dividedup into narrow strips and wound on to magazine rolls or made up intofilters immediately.

For certain purposes, for the production of webs of filtering materialfor instance, perforation of the flat material may be desirable. This issuitably done before the web of material has been made yielding or afterit has been re-hardened with or without aftertreatment subsequent to thecrimping and stretching process. For such webs of filtering material itmay also be advantageous to interrupt the regular grooving of thecrimped material, which can be done by means of a second grooving withthe grooves running in a different direction. This cross grooving mustof course also be effected when the material is still yielding. Finally,it should also be pointed out that for filtering purposes the materialcan be so vigorously stretched that randomly distributed tears, cracksand holes are produced in the crimped web.

FIGS. 1 and 2 illustrate a typical embodiment of an arrangement forproducing endless webs of filtering material with longitudinal crimping,suitable for the efiicient manufacture of filter plugs. In thisarrangement the smooth web of material 1, made of absorbent paper forinstance, runs from the delivery roll 2 through a perforator consistingof a toothed roller 3 and a corresponding counter roller 4, or of othersuitable perforating members. After passing through this perforator theweb of material has ragged holes as shown in FIGS. 3 and 4. Theperforated web then passes into a device 5, in which it is, forinstance, moistened or treated with aqueous steam so as to give it thedesired yieldingness. Furthermore, the tensile strength of the web ofmaterial must of course be great enough to ensure the faultless passageof the said material through the entire arrangement.

The web of material which has been made yielding and perforated is thendeformed in a multi-stage crimping and stretching apparatus 6. Here itis assumed that stamping is effected by a number of pairs of rollers,the first of which is designated 7, 8 and the last 9, 10. In order toobtain a reduction in width, which is presumed to be desirable, thedistance between the stamping edges of each successive pair of rollersis shortened. The same effect is achieved by increasing the speed of theroller pair 9, 10 in relation to that of the roller pair 7, 8. Thereduction in width of the web of material will not necessarily be aslarge as indicated in FIGS. 1 and 2. Particularly when the material isvigorously stretched, the web width shown by dot-dash lines will result.

FIGS. 5, 6 illustrate the apperance of the web bf material 1 after ithas passed through the first pair of rollers 7, 8 and FIGS. 7 and 8after it has passed through the last pair of rollers 9, 10. According tothe configuration of the stamping rollers, the thickness of the materialcan be greater either at the groove edges, as shown in FIG. 11, or atthe walls, as shown in FIG. 12.

After leaving the crimping and stretching apparatus 6 the longitudinallycorrugated and perforated web of material 1 passes through a pair ofrollers 11, 12-pricking or knurled rollers, or others of suitableconfigurationwhich deform the regular longitudinal crimped folds in anirregular manner so that the longitudinally corrugated web of materialpossesses a plurality of longitudinal grooves which run into oneanother, as indicated in FIGS. 9 and 10. Next, the web of material 1passes into an aftertreatment apparatus, which here consists of a dryingplate 13 with electric heating element 14. The longitudinally crimpedweb-of material 1 can be easily damaged in its yielding state and musttherefore not be pressed against the drying plate 13 by mechanicalmeans. Instead, an air stream directed via the nozzles 15 against theweb of material 1 is provided for the purpose. This air stream can, inits turn, be heated if desired or can also be used to cool the web ofmaterial 1.

Normally, a reduction in the width of the longitudinally crimped web ofmaterial occurs while the latter is being dried (not illustrated inFIGS. 1 and 2). If desired, this effect can be enhanced still further bygently compressing the web of material from the side, e.g. by means oflateral streams of compressed air ejected from special nozzles. Theextent of the lateral contraction of the drying web also depends, ofcourse, on the type of material, as well as on the changes in thicknesscaused by the stretching process, which changes are, in their turn,determined by the shape of the stamping grooves.

If desired, the hardened web of material 1 coming from theaftertreatment apparatus can pass through a second perforator consistingof the rollers 16, 17, in which case the first perforator 3, 4 maypossibly be omitted. The web of material 1, which has thus received itsfinal form, is now subdivided by rotating cutter blocks 18, 19 intothree strips la, 1b, 10 which are wound on to magazine spools 20, 21,22.

The arrangement shown in FIGS. 1 and 2 can be substantially simplified,according to the type of the web of material to be worked and thepurpose intended for the strip filtering material produced. By way ofexample, the perforators 3, 4 and 16, 17 can be completely dispensedwith, particularly if randomly distributed cracks and holes are producedby adequately vigorous stretching of the material. Furthermore, groovingwith only one pair of stamping rollers 7, 8 already yields a perfectlyusable, longitudinally corrugated web of material, the width of theoriginal smooth web remaining virtually unchanged. In this case, to besure, it is advisable to employ a fineknurled pair of rollers 11, 12 soas to avoid through longitudinal ducts.

FIG. 13 shows a photograph of four samples of material, A, B, C and Dwhich were produced with an arrangement of the type described above andhaving only one pair of stamping rollers. With all four samples crrmplngwas effected in the same manner; with samples A and B, however,perforation was effected before or after the crimping and stretchingprocess respectively, but treatment with a knurled roller was dispensedwith. C and D are samples of a crimped and stretched web of materialsubsequently treated with a coarse or fine knurled roller respectively.In all cases the longitudinal grooving is clearly visible, the materialherea thin blotting paperbeing so vigorously stretched that large cracksoccur, which greatly facilitates the gathering of the webs of material,which is done transverse to the longitudinal di rection of the grooves,and yields highly efiective filter cords. In addition, the longitudinalstructure consisting of an alternately larger and smaller materialthickness transverse to the longitudinal direction of the groove isclearly recognizable.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is:

1. As an article of manufacture, an absorbent sheet for making filtersfor cigarettes, comprising a web of an elongated fibrous strip materialhaving a plurality of parallel adjacent strips of alternately greaterand lesser density of said strip material extending substantiallyparallel to the longitudinal dimension of said web and having superposedthereonto crimping grooves, the crimping ratio, taken transversely tothe direction of the grooves, of a strip when in crimped condition to acrimped strip when ironed flat being in the range of 1:1 to 1:2, saidstrips being provided with a plurality of spaced cracks therein runningsubstantially in the direction of said grooves.

2. As an article of manufacture, an absorbent sheet for making filtersfor cigarettes, comprising an elongated web of fibrous strip materialhaving a plurality of parallel adjacent strips of alternately greaterand lesser density of said material, said strips extending substantiallyparallel to the longitudinal dimension of said web and having superposedthereonto crimping grooves, said strips each being provided with aplurality of cracks therein at spaced locations and runningsubstantially in the direction of said grooves, the weight ratio of aportion of predetermined area of a strip when in crimped condition to aportion of like area of a crimped strip when ironed flat being in therange of 1:1 to 2:1.

3. As an article of manufacture, an absorbent sheet for making filterscomprising, a web of elongated fibrous strip material having a pluralityof parallel adjacent strips of alternately greater and lesser density ofsaid material, said strips extending substantially parallel to thelongitudinal dimension of said web and having superposed thereontocrimping groovess extending substantially parallel to said strips, saidstrips at the upper and lower edges of said crimping grooves beingthicker than at the walls of said grooves intermediate said edges, saidstrips being provided with a plurality of spaced cracks therein runningsubstantially in the direction of said grooves.

4. As an article of manufacture, an absorbent sheet for making cigarettefilters comprising, a web of elongated fibrous strip material having aplurality of parallel adjacent strips of greater and lesser density ofsaid material, said strips extending substantially parallel to thelongitudinal dimension of said web and having superposed thereontocrimping grooves, all of said strips being provided with a plurality ofperforations running substantially in the direction of said grooves andhaving ragged borders.

5. An absorbent sheet for making cigarette filters comprising anelongated web of fibrous sheet material having closely spacedlongitudinal crimping grooves set therein, having, for each groove andsubstantially parallel thereto, a plurality of adjacent strips ofalternately greater and lesser density of the sheet material, and alsohaving throughout the extent of said web a plurality of randomlydistributed interrupted longitudinal tears produced by a lateralstretching of said web beyond its elastic limit during formation of saidgrooves.

References Cited in the file of this patent UNITED STATES PATENTS1,929,008 Wells Oct. 3, 1933 2,001,023 Howell et al. May 14, 19352,033,867 Segal Mar. 10, 1936 2,075,386 Woodford Mar. 30, 1937 2,113,431Milliken Apr. 5. 1938 2,161,092 Rowe June 6, 1939 2,164,702 DavidsonJuly 4, 1939 2,224,713 Rowe et al. Dec. 10, 1940 2,494,334 Dorst Jan.10, 1950 2,502,112 Walker Mar. 28, 1950 2,834,809 Schutte et al. May 13,1958 2,849,932 Marogg Sept. 2, 1958 FOREIGN PATENTS 265,825 SwitzerlandMar. 16, 1950

1. AS AN ARTICLE OF MANUFACTURE, AN ABSORBENT SHEET FOR MAKING FILTERSFOR CIGARETTES, COMPRISING A WEB OF AN ELONGATED FIBROUS STRIP MATERIALHAVING A PLURALITY OF PARALLEL ADJACENT STRIPS OF ALTERNATELY GREATERAND LESSER DENSITY OF SAID STRIP MATERIAL EXTENDING SUBSTANTIALLYPARALLEL TO THE LONGITUDINAL DIMENSION OF SAID WEB AND HAVING SUPERPOSEDTHEREONTO CRIMPING GROOVES, THE CRIMPING RATIO, TAKEN TRANSVERSELY TOTHE DIRECTION OF THE GROOVES, OF A STRIP WHEN IN CRIMPED CONDITION TO ACRIMPED STRIP WHEN IRONED FLAT BEING IN THE RANGE OF 1:1 TO 1:2, SAIDSTRIPS BEING PROVIDED WITH A PLURALITY OF SPACED CRACKS THEREIN RUNNINGSUBSTANTIALLY IN THE DIRECTION OF SAID GROOVES.